Frequency-Modulated-Continuous-Wave (FMCW) radar is a type of radar system where a known stable frequency, continuous wave varies up and down in frequency over a fixed period of time by a modulating signal. A frequency difference between the receive signal and the transmit signal increases with delay, and hence with distance. The radar system then mixes echoes from a target with the transmitted signal to produce a beat signal which will give the distance of the target after demodulation.